PHOTOSYNTHESISCompiled by :

Raja Novi AriskaPendidikan Biologi

carbon dioxide

sunlight

oxygenREACTANTFROM AIR

TO AIR ORUSED FORRESPIRATIONPRODUCT

1. Definition of Photosynthesis Photo means

‘light’ andsynthesis means‘to make’

Process in whichplants convertcarbon dioxideand water intosugars usingsolar energy

water

glucose

photosynthesis

REACTANTFROM SOIL

USED BY PLANTPRODUCT

Photo means‘light’ andsynthesis means‘to make’

Process in whichplants convertcarbon dioxideand water intosugars usingsolar energy

2. Chemical process of photosynthesis

6H2O + 6CO2 C6H12O6 + 6O2 + 6H2OSun lightSun light

ChlorophyllChlorophyll

3. Photosynthesis Machinery

a. Chloroplasts

b. Chlorophyll- Absorbs red & blue light- Reflects green light

4. Mechanism of Photosynthesis

1. Happen only insunlight

– Hence they depend onlight.

2. Light is absorbed bychlorophyll molecules

3. The energy generatesmolecules of ATP

4. Including PS I and PSII

a. Light (dependent)Reactionsa. Light (dependent)Reactions1. Happen only in

sunlight– Hence they depend on

light.2. Light is absorbed by

chlorophyll molecules3. The energy generates

molecules of ATP4. Including PS I and PS

II

Components Inside the Thylakoid1. PS II : absorb wavelength 680 nm. Composed

of complex antenna and chlorophyll.2. Plastoquinon (PQ)enzyme.3. Cytochrome b6f Complex.4. Plastocyanin enzyme5. PS I : absorb wavelength 700 nm. Composed

of complex antenna and chlorophyll.6. Ferredoxin (Fd) enzyme.7. Ferredoxin NADP Reductase.8. ATP Synthase Complex.

1. PS II : absorb wavelength 680 nm. Composedof complex antenna and chlorophyll.

2. Plastoquinon (PQ)enzyme.3. Cytochrome b6f Complex.4. Plastocyanin enzyme5. PS I : absorb wavelength 700 nm. Composed

of complex antenna and chlorophyll.6. Ferredoxin (Fd) enzyme.7. Ferredoxin NADP Reductase.8. ATP Synthase Complex.

The differences between PS I and PS IIPhotosystem I Photosystem II

Used4 photons1 ADP1 Phosphate1 H2O1NADP+

2 photons1 ADP1 Phosphate

Product1 ATP1 NADPH + H+

½ O2

Product1 ATP1 NADPH + H+

½ O2

1 ATP

ReactionCapture energy in theformation of ATP andNADPH, hydrogentransfer in dark reaction

Capture energy in theformation of ATP

Wavelength 700 nm 680 nm

b. Light Independent Reactions

• Happen in sunlight, andin the dark.

– Hence “independent oflight”

1. ATP generated bysunlight drives theCalvin Cycle.

2. Monosaccarides (eg.glucose) aremanufactured in thecycle.

3. Monosaccarides areused to “build”polysaccharides (eg.Starch).

• Happen in sunlight, andin the dark.

– Hence “independent oflight”

1. ATP generated bysunlight drives theCalvin Cycle.

2. Monosaccarides (eg.glucose) aremanufactured in thecycle.

3. Monosaccarides areused to “build”polysaccharides (eg.Starch).

C4 Cycle• In C4 plants, it increase photosynthetic yield two to

three times more than C3 plants.• In C4 plants, it performs a high rate of photosynthesis

even when the stomata are nearly closed.• It increases the adaptability of C4 plant to high

temperature and light intensity.• It increases the rate of CO2 fixation at 25° - 30°C in

C4 plants as compared to C3 plants.• It reduces the rate of photorespiration at 25° - 30°C.• Example of C4 plants : rice, corn, weat, sugarcane,

etc.

• In C4 plants, it increase photosynthetic yield two tothree times more than C3 plants.

• In C4 plants, it performs a high rate of photosynthesiseven when the stomata are nearly closed.

• It increases the adaptability of C4 plant to hightemperature and light intensity.

• It increases the rate of CO2 fixation at 25° - 30°C inC4 plants as compared to C3 plants.

• It reduces the rate of photorespiration at 25° - 30°C.• Example of C4 plants : rice, corn, weat, sugarcane,

etc.

Hatch-Slack Cycle

The Differences Between C3 Cycle with C4 Cycle

No. C3 Cycle C4 Cycle1. The primary CO2 acceptor is a

5C compound ribulosebiphosphate (RuBP).

The primary CO2 acceptor is a 3Ccompound phosphoenol pyruvic acid(PEP).

2. The first stable compoundformed is phosphoglyceric acid(PGA) which contain 3C atoms.

The first stable compound formed isa 4C Oxaloacetic acid (OAA).

3. C3 cycle is completed in onlyone type of chloroplast presentin mesophyll cell.

C3 cycle is completed in to types ofchloroplast, one occurring inmesophyll cells and other in bundlesheath cells.

C3 cycle is completed in onlyone type of chloroplast presentin mesophyll cell.

C3 cycle is completed in to types ofchloroplast, one occurring inmesophyll cells and other in bundlesheath cells.

4. It takes place at comparativelylow temperature.

It takes place at high temperature andmore light intensities.

5. Photorespiration occurs in C3plants.

Photorespiration is not occurs in C4plants.

6. The rate of photosynthesis iscomparatively lower.

The rate of photosynthesis iscomparatively higher.

7. It occurs in C3 plants whichshow normal anatomy.

It occurs in C3 plants which showKranz anatomy.

5. Factors Affecting Photosynthesis Rate

External factors

1. Light intensity2. Carbondioxide

concentration3. Temperature4. Water

Internal factors

1. Chlorophyll2. Protoplasm3. Photosynthesis product

(photosynthate)

1. Light intensity2. Carbondioxide

concentration3. Temperature4. Water

1. Chlorophyll2. Protoplasm3. Photosynthesis product

(photosynthate)

6. Photosynthesis Experiment

Ingenhousz experiment(1799) photosynthesisproduces Oxygen (O2)

Sachs experiment (1860)

“Photosynthesisproduces amilum”